I have this annoying problem -- in my local zsh and screen everything is
OK.  But when I log into certain Red Hat 7.2 boxen from a window in that
screen, and start vi, backspace produces ^?.  Note that *remote* shell is
zsh and backspace in its command line works just fine.

I dug out the solution for (the local) screen -- tell it

bindkey ^? stuff ^H

That fixes the remote vi, keeps remote zsh happy, but breaks the local
screen itself fscking up ^A <backspace> which no longer moves to the
previous window until it eats an extra key press or something.

I wonder whether this is a problem which can be fixed on zsh's own bindkey
level?

Cheers,
Alexy